2024-03-21

Last modified: 2024-03-21 14:43:45

Ballnuts

I'm going to attempt to put the ballnuts back together, preferably without losing any of the balls.

First one went well! I greased up the inside of the ballnut, inserted the diverters, then counted the balls into their tracks using tweezers. I put 17 on the outer tracks and 16 on the middle one. Then noted the position of the thread start point on the screw and nut and, with the screw held upright with a clamp, carefully threaded the nut on. I did not lose any (more) balls.

Update: I put the nut on backwards. It wants the flange end furthest from the motor coupling.

I removed it, reversed it, and tried to put it back on but had a lot of trouble. I kept having one or two balls falling out of place. Eventually I got it on, I think the key was to remove grease from the screw, so that the balls stick to the nut and don't stick to the screw.

Then with the nut on the screw, pack some more grease in, wind the nut back and forth to distribute the grease, screw on the seals, and put in the grub screws for the seals.

I'm not satisfied with the 3d-printed seals, they're too tight. Both internal and external diameter are too large. I have managed to get them both in, but I'm driving the nut back and forth with the cordless drill and the screw is getting quite hot. I will modify the seal design and reprint them, but for now I'll move on to assembling the other nuts.

All 3 ballnuts have 3.16mm balls. Probably that is just slightly-undersized for 1/8 of an inch.

The second ballnut went on first try! And with all 51 balls. Great success. I haven't put any more grease in that one yet, pending new seals.

On the third one I put 17 balls on each of the first 2 tracks, and only 9 balls on the track closest to the flange.

So now I want some new seals, then I'm done preparing ballscrews and I can move on to making the frame parts out of Minerva.